Summer Hot Tub Care: How to Prevent Algae in Warmer Weather

Hot tubs often receive more use during the summer, particularly when friends and family are visiting or the evenings remain warm and light. However, increased use, higher temperatures and contaminants such as sun cream can place additional pressure on the water and filtration system.

Without the right maintenance routine, clear water can quickly become cloudy, discoloured or unpleasant. In some cases, algae may begin to develop.

The good news is that most summer water problems are preventable. A few regular checks can help keep your hot tub clean, comfortable and ready to use throughout the warmer months.

Why Hot Tub Water Needs Extra Attention In Summer

A hot tub is a relatively small volume of warm water. This means its chemical balance can change much more quickly than the water in a swimming pool.

During the summer, the hot tub may also receive a higher number of bathers. Every person introduces small amounts of sweat, body oils, cosmetics, deodorant and other organic matter into the water. Sun cream and moisturiser can be especially troublesome because they collect in the water, place pressure on the sanitiser and gradually clog the filter.

Warm conditions, low sanitiser levels and poor circulation can create an environment in which algae and other unwanted microorganisms can develop. Regular testing and cleaning, therefore, become particularly important when the hot tub is being used frequently.

What Causes Algae In A Hot Tub?

Algae usually develops when the water is not being sanitised, circulated or filtered effectively.

• Common contributing factors include:
• Low chlorine or bromine levels
• Incorrect pH
• A dirty or blocked filter
• Insufficient filtration cycles
• Leaves, pollen and other debris entering the water
• Heavy or frequent use
• Sun cream, cosmetics and body oils
• Leaving the hot tub uncovered for long periods
• Poorly maintained pipework or hidden biofilm

Green water is often associated with algae, but colour alone does not confirm the cause. Metals in the water can also produce a green or tinted appearance. Testing the water and looking at its overall condition will help determine the correct treatment.

Test The Water More Frequently

Weekly testing may be sufficient when a hot tub is receiving light use, but summer usage can change the water balance much faster.

Test the water regularly and always check it following a period of heavy use. Pay attention to the sanitiser, pH and total alkalinity readings.

Your hot tub manufacturer or water-treatment supplier should provide the recommended ranges for the chemicals and system you use. Avoid adding products without testing first, as continually adding chemicals without understanding the underlying imbalance can make the problem more difficult to correct.

A high pH can reduce the effectiveness of chlorine, while a low pH may cause discomfort and contribute to equipment corrosion. Keeping the water balanced helps the sanitiser work properly and protects the hot tub’s internal components.

Maintain The Correct Sanitiser Level

Chlorine and bromine help control bacteria and other contaminants in hot tub water. However, the sanitiser is gradually used up as it deals with material introduced by bathers.

During busy periods, the sanitiser level may fall much faster than expected. This can leave the water vulnerable even when it looked perfectly clear earlier in the day.

Check the level before use and again following a busy session. Add the appropriate product in accordance with the manufacturer’s instructions, allowing the water to circulate fully before retesting.

Never assume that a strong chemical smell means there is too much chlorine. An unpleasant odour can sometimes indicate that the available sanitiser has reacted with contaminants and the water requires attention.

Clean The Filters Regularly

The filters collect hair, dirt, oils and fine debris as water passes through the system. When they become dirty, circulation is restricted and water quality can deteriorate.

During summer, rinse the filters frequently using clean water. A deeper clean with a suitable filter-cleaning product should also form part of the maintenance routine.

Avoid using ordinary washing-up liquid or household cleaning products. These may leave residues that cause persistent foam when the filters are returned to the hot tub.

Filters do not last indefinitely. Replace them when the pleats remain discoloured after cleaning, the material becomes damaged or the filter can no longer maintain adequate water flow.

Keep The Hot Tub Covered When It Is Not In Use

Leaving the cover off may make the hot tub appear more inviting, but it also allows pollen, dust, insects, leaves and bird debris to enter the water.

An effective cover reduces contamination and helps protect the water between uses. It also prevents unnecessary heat loss and reduces the amount of energy required to maintain the selected temperature.

Clean the cover regularly and remove any standing water or debris. Check for cracks, sagging or damage that may be affecting its fit and insulation.

Encourage Bathers To Shower First

A quick shower before entering the hot tub can significantly reduce the amount of sweat, sun cream, make-up, deodorant and body oil entering the water.

This small step can reduce the demand on the sanitiser, help filters remain cleaner and lower the likelihood of foam or a greasy line developing around the shell.

Where possible, apply sun cream after using the hot tub rather than immediately beforehand. When that is not practical, shower thoroughly before entering.

Check The Filtration Schedule

The filtration system needs enough time to remove contaminants from the water. If the hot tub is being used more frequently, its usual filtration schedule may no longer be sufficient.

Consult the manufacturer’s guidance before changing the settings. Some systems automatically adjust filtration, while others require the owner to increase the duration or frequency manually.

Poor circulation can also indicate a blocked filter, low water level, air lock or pump problem. If the jets appear weaker than normal or the hot tub displays a flow-related error, investigate the issue promptly rather than continuing to use it.

Remove Debris Before It Becomes A Problem

Use a suitable net or vacuum to remove leaves, insects and other visible debris. Wipe the waterline regularly with a hot-tub-safe cleaning product to prevent oils and residues from building up around the shell.

Do not use ordinary kitchen or bathroom cleaners. Household products can affect the water chemistry, generate foam and potentially damage the hot tub’s surfaces.

Keeping the surrounding area clean can also reduce the amount of grass, soil and garden debris carried into the water.

What To Do If The Water Starts Turning Green

Stop using the hot tub until the cause has been identified and the water has been treated.

Begin by checking:

• The chlorine or bromine level
• The pH and alkalinity
• The condition of the filter
• Whether the circulation system is operating correctly
• Whether the water is cloudy, slimy or producing an unusual smell

If algae is suspected, the water may need to be treated with the appropriate shock product, followed by thorough filtration and filter cleaning. Always use products that are suitable for your hot tub and follow the dosage and safety instructions carefully.

Where the water is heavily contaminated, has remained untreated for an extended period or does not improve after corrective treatment, draining and thoroughly cleaning the system may be the safest solution. This can include cleaning the internal pipework before refilling.

Do not mix different chemical products together or add several treatments at the same time unless the instructions explicitly state that it is safe to do so.

When Should You Call a Hot Tub Professional?

Professional help is recommended when:

• The water remains green or cloudy after treatment
• The sanitiser level repeatedly falls soon after dosing
• There is visible slime or persistent biofilm
• The filter or pump is not maintaining adequate circulation
• The hot tub produces recurring error codes
• There is an unusual smell that does not disappear after treatment
• You are unsure which products are compatible with the system

A recurring water problem may be caused by more than a simple chemical imbalance. Restricted flow, ageing filters, ineffective circulation or contamination inside the plumbing may need further investigation.

A Simple Summer Hot Tub Care Routine

A consistent routine is more effective than waiting for the water to change colour.

Before use:

• Check that the water is clear and the hot tub is circulating correctly
• Test the sanitiser and pH
• Remove any visible debris

After heavy use:

• Retest the water
• Adjust the sanitiser where necessary
• Check the waterline for oils or residue

Each week:

• Rinse the filters
• Clean the waterline
• Inspect the cover
• Check the filtration settings and water level

At regular service intervals:

• Deep-clean the filters
• Inspect the pumps, heater and circulation system
• Drain and refill the hot tub when required
• Arrange professional maintenance where appropriate

Keep your hot tub ready for summer

Summer hot tub care does not need to be complicated, but the water should not be left unchecked during periods of frequent use.

Regular testing, effective filtration and good bather hygiene can prevent many of the most common problems. Acting quickly when the water changes appearance can also avoid a more disruptive drain, clean and refill later.

If your hot tub water has become green, cloudy or difficult to balance, MG Hot Tubs can inspect the system, identify the likely cause and recommend the appropriate treatment or repair.

Contact MG Hot Tubs for professional hot tub servicing, water-care advice and repairs across Sussex, Kent and the surrounding areas.